In recent years, advances in technology, as well as environmental concerns and ever evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the power usage and complexity of the various electrical systems within automobiles, particularly alternative fuel vehicles, such as hybrid, electric, and fuel cell vehicles. Such vehicles often use two separate voltage sources, for example, a battery and a fuel cell, to power the electric motors that drive the wheels.
In July 2006 there were between 60,000 and 76,000 battery powered vehicles in use in the United States, increasing to an estimated over 100,000 battery powered vehicles in use today. Typically, one or more batteries provide electrical power, which is converted into mechanical power for turning the wheels. When the energy in the battery is depleted, the battery may be recharged.
Hydrogen fuel cells used to power cars with electric motors are two to three times more efficient than gas powered internal combustion engines, have zero-emissions, and are quiet and vibration free. Hydrogen is readily found, and may be extracted from natural gas, coal, crude oil, and the like, but preferably may be produced from water by a pollution free process of electrolysis.
Electricity from a fuel cell is created in a chemical reaction that occurs when hydrogen and oxygen are combined, with water being the only byproduct. To power a vehicle, typically hundreds of fuel cells are stacked together in series, combining their individual electrical outputs. Hydrogen typically is stored under pressure aboard the vehicle and supplied to the fuel cells under reduced pressure. However, energy is lost (wasted) when converted from a high pressure to the lower pressure for supplying the fuel cell.
Typically, known systems use a flow regulator and injectors, with pressure energy being wasted. Other known compressed air energy storage systems have used gas burners to preheat air during the expansion process, using only this source for energy output.
Yet another known system, disclosed in U.S. Pat. No. 6,706,439 assigned to the assignee of the present disclosure, returns the non-consumed hydrogen to storage, but does not utilize the pressure of expanding hydrogen.
Accordingly, it is desirable to provide a more efficient method and system for converting pressurized hydrogen to electricity for recharging the battery of an electric vehicle. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.